1. Technical Field
The present invention relates to an improved information-retrieval method and system. In particular, the present invention relates to an improved digitally-based information-retrieval method and system. More particularly, the present invention relates to digital video discs and digital video disc drives. Still more particularly, the present invention relates to a method and system for conserving laser power after the retrieval of digital video data from digital video discs and to a method and system for extending the operating life of digital video disc drives.
2. Description of the Related Art
The digital video disc (DVD) is the next generation of optical disc storage technology, which succeeds where compact disc (CD) technology, including CD-ROM technology, ended. Within digital video disc technology, audio, computer, and video data can be encoded onto a digital video disc, which appears visually to resemble a CD or CD-ROM, but which stores a much greater amount of data. A typical digital video disc stores greater amounts of data than traditional CDs. A standard, single-layer, single-side digital video disc, for example, can store 4.7 GB of data, while a two-layer standard digital video disc increases the single-sided disc capacity to 8.5 GB. Digital video discs may be composed of double-sided discs having a storage capacity of approximately 17 GB per disc. Or course, as technology advances, this storage capacity will increase. (Note that the acronym "DVD" can equally represent the term "Digital Versatile Disc" as well as the term "Digital Video Disc".)
A problem associated with digital video disc drives which retrieve video data and other associated data (i.e., audio data, computer data, etc.) from digital video discs involves the power required by a laser light source to successively read multiple interior data layers of typical digital video discs. Some digital video disc drives may require an increase in the laser power required to successively reading these multiple interior layers. This increase in laser power is necessary to increase the signal-to-noise ratio inherent with reading data from optical storage discs and to compensate for the absence of an aberration compensator in the optical path.
Any increase in laser power leads to a shortening in the life of the laser, because the laser's life is inversely proportional the power levels at which it operates. When the laser power is increased geometrically according to the number interior layers being read, the laser life is unduly shortened because the laser remains constantly in a power-on tracking mode for a given interior layer, even after all the video data and other associated data has been read from that particular interior layer. Even during quiescent or transition periods prior to focusing the laser on a subsequent layer, and hence a subsequent track of the digital video disc in use, the digital video disc drive laser continues to operate at that power level.
Based on the foregoing, it can be appreciated that a need exists for a method and system which would effectively decrease the power level at which a laser light source operates after a reading of video data and other associated data contained within multiple layers of an optical storage disc, such as a digital video disc. Such a method and system, if implemented, would result in an increase in the life of laser light sources utilized in association with optical storage device drives, such as DVD drives.